LBZ: CHANGE FUEL FILTER (not asking how to)

4x4le

New member
I hope this is more of a question and not a problem but I want some insite on what might be wrong.

I just bought my truck the other day from a chevy dealer used with 117k miles on the clock. They had a service sheet of what all they did to it when they got it. Fuel filter, oil change, changed the stock work truck wheels and tires to aftermarket wheels and tires ect.
They did use the truck one time to haul a car supposedly and the oil life showed around 82% and fuel filter showed 92% which seems right if they used the truck for something depending on how much it had been driven. The fuel filter looks new (I know it could have been cleaned off and the dic reset but I doubted that).
Well today on a country hwy there was a combine harvester slowing down traffic and when I got the chance to pass I got into the truck for the first time since test driving it. The DIC showed change "fuel filter" and when I stopped it said 0% fuel filter life remaining. I reset it because I dont have one, wasnt home and there was not a parts store between my location and home. I am home now and it still reads 100%. The plastic screw is tight and no leaks on the assembly.

Can someone explain this or offer their input on what your next steps would be. Its stock but did I starve the injector pump and would that cause it to think the filter is clogged?
 

4x4le

New member
so does it figure it needs changed based on actual rail pressure vs what it wants to see or if the IP is sucking too hard or both?

I was actually under the impression that it was calculated by hours and miles and nothing else had any bearing on the DIC's indicated filter life so if thats true it was a glitch which my DIC on my 2011 chevy has had glitches.

Fuel was bought at a high volume station that I use for my powerstroke however I have no monitor for this problem in that truck and they are different engines and they could have got a bad batch.

Im just trying to think out what tripped it out as this is a new platform for me.
 

chevyburnout1

Fixing it till it breaks
Aug 25, 2008
2,368
1
38
Berthoud, CO
The fuel filter life is based off of a few things including hours and how you drive it. However if the percentage dropped that quick it means fuel rail pressure dropped off from commanded for too long. Usually it sets a P0087-"Low Fuel Rail Pressure" or a P1093-"Fuel Pressure Low During Power Enrichment" and puts your truck into a fail safe mode. I would start with a fuel filter as well.
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,205
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I just looked at the pictures you posted in your introduction thread, and I notice you actually have an LMM instead of an LBZ. On those trucks, if you have a low rail pressure condition, it will drop the filter life to 0%.
 

2006duramax

2006duramax
Sep 6, 2012
26
0
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30
Scottsbluff Nebraska
Buy a cat filter swap. Best thing I ever did cheaper long lasting filters that filter way better than stock. Kits under 100 buck and well pay itself off fast...I got mine off aligator performance.com
 

4x4le

New member
Something else I just thought about is I was on hilly terrain and my fuel level was between 1/2 and 1/4. Could it have sloshed and picked up a touch of air? I do not have an exhaust system yet so it isnt really possible to hear any hickups.

I did put it in tow haul when I passed too as I have heard guys do that when they race because the converter locks up earlier, not sure if it matters but I did that too right before I passed.

Right now I have a full tank and I reset the filter life and I might give it a little hell just to see if I can re-create the issue tomorrow night on my way to work.

I just looked at the pictures you posted in your introduction thread, and I notice you actually have an LMM instead of an LBZ. On those trucks, if you have a low rail pressure condition, it will drop the filter life to 0%.
What makes you say I have a LMM? Just curious because I dont have a keen eye on these yet. My build date was 03/07 and my VIN's 8th digit is a 6 so this told me I have a LBZ. The condition you say the LMM can trip with low rail pressure is just about exactly like what happened to me though.

Buy a cat filter swap. Best thing I ever did cheaper long lasting filters that filter way better than stock. Kits under 100 buck and well pay itself off fast...I got mine off aligator performance.com
It was something I had plans on researching which I guess Ill go ahead and do now. Its one of the reasons I was hesitant about changing the filter right now since I shouldnt have to and if Im going to mod that I should do it right away.
 

Harbin_22

Active member
Dec 4, 2010
3,856
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Southern Indiana
Yeah you definitely have an LMM. All of the new body style 07-10's are LMM. I would change the filter and go from there. If the filter doesn't fix it, look at all the soft fuel lines from the tank all the way up to the filter. They can get kinked and sometimes they get too soft and collapse under hard acceleration. These do not have an electric fuel pump stock, so the injection pump is sucking fuel all the way from the tank.
 

4x4le

New member
Apparently the thing I looked up before buying the truck had the wrong number for engine identification in the vin number. What Im seeing now on other web sites is that with my vin I do have a LMM so I dont know if this changes things or if my thread needs moved or if the title needs changed.

Now I need to do some research on LMM's because prior to buying the truck my research was on lbz's. Hopefully they are better engines or Im not in for a supprise when researching them. This is disheartning because I thought I did my research but was mislead by the engine identification by vin page that I had printed off.............
 

Harbin_22

Active member
Dec 4, 2010
3,856
6
38
Southern Indiana
They are almost identical in hard parts other then emission stuff and injectors. They other way to tell what engine you have is look in the glove box door and there is a tag that has all the codes for the build. LMM will be in there. They are pretty well rounded engines all in all.
 

jc1843

New member
Sep 27, 2009
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So Calf
Look on the driver's side valve cover -- there are two fuel lines where the lines come from the fuel tank. The rubber hoses in that area can get kinked, and can collapse, that causes a fuel restriction.
 

4x4le

New member
Thanks. Ill check that out.

I got around to looking at the lift pumps and stuff. If I got the cat adapter would it be as necessary to then run a pre filter on the lift pump? The cat one said its at 2 microns already. This could be a cheaper option. The cat one does not have the water separator thing on it but does it separate water still?
 

SoCalMike

Member
Dec 11, 2010
747
7
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SoCal
No it does not. you can run a donaldson p553203 on your cat adapter. it is a 3 micron fuel filter and water separator.
 

4x4le

New member
Cool. Great info. I figure I will just order the adapter and have it ready for when I do change the filter. I did notice that the adapter comes with a cat filter already. As long as I make sure the fuel stations I go to are quality stations I should be fine with that filter correct? Or is the use of those filters for people that are running inline water separators?
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,205
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Texas!!!
I would not run without some sort of water separator. Water is probably the biggest cause of injector damage.
 

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